Reinforcing element for concrete construction

ABSTRACT

A reinforcing element for concrete construction in the form of a set bolt which is formed of a rod-shaped section with a cross-sectional enlargement on the end is provided. Significantly, at least this cross-sectional enlargement is formed of glass-fibre reinforced plastic and has an axial bore in its centre, and that the bore and the area of the rod-shaped section surrounded by it engage with one another in a form-locking manner.

BACKGROUND

The invention relates to a reinforcing element for concrete construction in the form of a set bolt which consists of a rod-shaped section with a cross-sectional enlargement on the end.

Set bolts of this type are primarily used to transfer compressive and transverse forces, however, they can also transfer tractive forces. They are predominantly used as shearing reinforcement or punching reinforcement in structural concrete parts, moreover, as compressive or transverse stress bars in insulating bodies which are inserted between a building ceiling and a projecting balcony platform.

To date, these set bolts consist of structural steel or, when there are corrosive influences, of high-grade steel, however, this considerably increases the manufacturing costs.

Recently, reinforcing bars are also manufactured from glass-fibre reinforced plastic, in particular, when it is a question of corrosion resistance or low heat conduction. In this case, it is duroplast which has a glass-fibre constituent of about 50% to 80% to obtain the desired strength. Since duroplast cannot be subsequently shaped, to date, reinforcing elements consisting of glass-fibre reinforced plastic have become known only in the form of bars with a constant cross section.

SUMMARY

It is now the object of the present invention to produce a reinforcing element in the form of a set bolt in which at least the head, i.e. the cross-sectional enlargement on the end, consists of glass-fibre reinforced plastic. The set bolt should thereby be distinguished by high stress absorption in direction of the strain and stress and economical to manufacture.

According to the invention, this object is solved in that at least the cross-sectional enlargement of the set bolt on the end consists of glass-fibre reinforced plastic and that an axial bore is situated in its centre and that this bore and the area of the rod-shaped section surrounded by it engage in one another in a form-locking manner.

While up to now the cross-sectional enlargement on the end is produced by compressing a cylindrical rod, according to the invention, a separate part is used for the cross-sectional enlargement and this separate part is engaged in a form-locking manner with the rod-shaped section of the set bolt. This ensures the transfer of high forces from the cross-sectional enlargement to the rod-shaped section even when the cross-sectional enlargement and, optionally, also the rod-shaped section is formed of plastic.

Generally, the transfer of tractive and compressive forces through the set bolt is in the fore, which is why it is advisable to form the form-locking engagement with a profiling which is primarily effective against axial forces, i.e. by transverse ribs, bores, milled recesses or threads.

To further promote the force transfer between rod-shaped section and cross-sectional enlargement on the end, an especially advantageous embodiment of the invention lies in that the cross-sectional enlargement has a tubular extension extending along its axial bore, namely in a length which corresponds at least to three times, preferably at least four times, the diameter of the bore.

This results in a large form-closed contact area is obtained between the two parts and, accordingly, a corresponding high transfer of force.

For the same purpose, it is advantageous that the tubular extension has an increasing wall thickness in direction of the cross-sectional enlargement, i.e. is formed conically, and at its end passes into the cross-sectional enlargement at an angle of less than 90°, in particular, of less than 60°.

If the closing shape between the rod-shaped section, on the one hand, and the tubular extension with its cross-sectional enlargement, on the other hand, are formed by threads, then it is possible to connect both parts to one another by screwing and subsequent gluing or fusing. However, it is especially advantageous if the cross-sectional enlargement, optionally with its tubular extension, is joined with the rod-shaped section by spraying on in a molten state. In particular, this applies even when the rod-shaped section itself consists of a glass-fibre reinforced plastic.

Finally, the present invention also relates to an insulating body which is equipped with the reinforcing elements described above and is inserted between two structural parts to be insulated, in particular, a building ceiling and a balcony platform. In this case, the corrosion-resistant properties of the glass-fibre reinforced plastics and its low heat conductivity are especially advantageous. The reinforcing element according to the invention can be used in the insulating body for the transfer of tractive, compressive and transverse forces.

To absorb transverse forces, it has been customary to date in insulating bodies to lead the corresponding reinforcing bars diagonally through the insulating body and to bend them back into the horizontal plane outside of said insulating body. Since this is rather difficult to do with reinforcing bars made of glass-fibre reinforced duroplast, i.e. the transverse bar must extend diagonally into the structural concrete part adjoining the insulating part, it is advantageous, for the optimal introduction of force into the structural concrete parts, to form the outer end of the cross-sectional enlargement by a plane which is diagonal to the axial direction of the transverse bar such that this plane extends more or less horizontally in the adjacent structural concrete part.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention can be found in the following description of embodiments with reference to the drawings, showing

FIG. 1 a side view in the end area of a set bolt;

FIG. 2 an axial section of FIG. 1;

FIG. 3 a side view according to FIG. 1, however, in an alternative embodiment;

FIG. 4 to FIG. 5 an insulating body with the set bolt according to the invention in a vertical section;

FIG. 6 to FIG. 9 possible applications for the set bolt according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 3 each show only the one end of a reinforcing element in the form of a head. The other end can look exactly the same, however, it can also be shaped differently or end as a normal reinforcing bar. The reinforcing bar or its illustrated rod-shaped section is designated with 1, the cross-sectional enlargement on the end with 2. As can be seen, the cross-sectional enlargement 2 is a self-contained part. It no longer has the conventional form but a tubular extension 2 a with which it surrounds the rod-shaped section 1.

An axial bore 3 runs in the centre of the cross-sectional enlargement 2 and its extension 2 a. In the embodiment, said axial bore 3 is continuous, however, it can also be in the form of a blind-end bore. The essential point is that, on the one hand, the outer side of the rod-shaped section 1 has a profiling 4 at least in the area inserted in the bore 3 and that the bore 3 has a profiling 5 corresponding thereto, so that both parts engage with one another in a form-locking manner.

This form-closing in combination with the tubular extension 2 a ensures an intimate connection and, accordingly, a high transfer of force between the two parts. As a result, both the reinforcing bar 1 and the cross-sectional enlargement 2 with its tubular extension 2 a can be made of a glass-fibre reinforced plastic.

In the embodiment, the profiling 4 and 5 is formed by threads. Thus, it would be possible to screw the cross-sectional enlargement 2 with its tubular extension 2 a onto the rod-shaped section 1 and to then connect both parts with one another. However, in most cases, it is more advantageous to insert the end of the rod-shaped section 1 into an injection-moulding tool and to spray the cross-sectional enlargement 2 with its tubular extension 2 a on in a molten state.

Preferably, the tubular extension 2 a also has a certain profiling on its outer side to promote its later connection with the concrete. To this end, its has several successive sections 6 or 7, stepped in their diameter, the diameter of which increases gradually in direction of the cross-sectional enlargement 2 in order to then pass into the cross-sectional enlargement 2 at an angle of less than 60°.

In FIG. 1, the sections 6 are separated from one another by a step extending peripherally in a screw-thread type manner, while the sections 7 in FIGS. 2 and 3 are separated by several steps extending peripherally in a circular manner. Of course, any other pro-filings desired are also possible in this case. The important point is only that the outer cross section of the extension 2 a increases, whether it be stepped or continuous. At the end, the extension 2 a then passes over into the substantially steeper cross-sectional enlargement 2, preferably with a thread angle of 30° to 60°.

FIGS. 4 and 5 show the use of the set bolt described above in insulating bodies. These insulating bodies are inserted between a building ceiling and a projecting balcony platform to minimize the heat flow between two structural parts. They are generally equipped with reinforcing elements for the transfer of tractive, compressive and transverse forces.

In the embodiments shown, one can see an insulating body 10 which is situated between a balcony platform 11 and a building ceiling 12. The insulating body 10 contains horizontally continuous tensile bars 13 as usual in its upper area, diagonally extending transverse bars 14 in its central area and horizontally continuous compressive bars 15 in its lower area.

It is now important that the aforementioned bars can consist entirely or partially of glass-fibre reinforced plastic due to the set bolts according to the invention, as can be seen in FIG. 4 for the preferred application for transverse and compressive bars.

FIG. 4 shows an alternative for the design of the set bolt. In the case of the transverse bars 14, they do not have any end faces extending at a right angle to the longitudinal axis of the bars, but diagonally extending end faces 14 a. Their diagonal position is selected such that both end faces 14 a lie in a horizontal plane. As a result, they can better absorb forces in vertical direction.

FIG. 5 shows the transverse bars with normal ends extending at a right angle to the axis of the bar.

In the case of the rod-shaped section 1, the plastic used for the present application consists of approx. 50% to approx. 80% glass fibres, the remainder of duroplast. In the case of the sprayed on head part, i.e. the cross-sectional enlargement 2 on the end and its tubular extension 2 a, it consists of approx. 20% to 60% glass fibres, the remainder of thermoplastic material.

FIG. 6 shows the vertical section through a concrete balcony 21 in which the four set bolts 22, each extending at a right angle to one another and parallel to the outer sides of the beam 21, serve to bind the statistically measured bending reinforcement which extends in horizontal direction in the beam, as replacement for a bracket encasement.

In the embodiment of FIG. 7 which shows a vertical section through a horizontally protruding console 32 attached to a column 31, the set bolts 33 serve to absorb the bending forces of the console 32 and to transfer them to the column 31 or its reinforcement 34, wherein the set bolts replace the structural parts usually designated as anchors which are loaded for tension in the upper console area and for pressure in the lower console area.

In FIG. 8, a bending-resistant frame corner 41 is also shown in a vertical section in which the set bolts 42 of the invention are used to replace brackets which are usually used at this point for reinforcement.

The embodiment shown in FIG. 9 shows set bolts 51, 52 according to the invention which are arranged vertically in a ceiling 54 situated on a support 53 and hereby extend between an upper grid reinforcement layer 55 and a lower grid reinforcement layer 56. The set bolts 51, 52 here serve as shearing reinforcement or punching reinforcement elements and carry the forces between ceiling and support away from the support toward the outside in a truss-like manner, so that the support is prevented from punching through the ceiling. In this case, the diameter enlargements on the end heads of the set bolts 51, 52 promote the transfer of force onto the respective grid reinforcing layers. 

1. A reinforcing element for concrete construction comprising a set bolt including a rod-shaped section (1) with a cross-sectional enlargement (2) on an end thereof, at least the cross-sectional enlargement (2) on the end is formed of glass-fibre reinforced plastic and has an axial bore (3) in a center thereof and the bore (3) and an area of the rod-shaped section (1) surrounded by the bore engage with one another in a form-locking manner.
 2. The reinforcing element according to claim 1, wherein the form-locking engagement is formed by a profiling (4, 5) effective primarily against axial forces.
 3. The reinforcing element according to claim 1, wherein the form-locking engagement is formed by threads (4, 5).
 4. The reinforcing element according to claim 1, wherein the cross-sectional enlargement (2) has a tubular extension (2 a) extending along the axial bore (3).
 5. The reinforcing element according to claim 4, wherein the tubular extension (2 a) has an axial length which corresponds to at least three times a diameter of the bore (3).
 6. The reinforcing element according to claim 4, wherein the tubular extension (2 a) is profiled on an outer side thereof.
 7. The reinforcing element according to claim 4, wherein the tubular extension (2 a) has a wall thickness that increases in a direction toward the cross-sectional enlargement (2).
 8. The reinforcing element according to claim 4, wherein the tubular extension (2 a) passes into the cross-sectional enlargement (2) at an angle of less than 90°.
 9. The reinforcing element according to claim 1, wherein the cross-sectional enlargement (2) is sprayed or injection-moulded onto the rod-shaped section (1).
 10. The reinforcing element according to claim 1, wherein the rod-shaped section (1) consists of glass-fibre reinforced plastic.
 11. The reinforcing element according to claim 1, further comprising an insulating body (10) for insertion between a building ceiling (12) and a balcony platform (11).
 12. The reinforcing element according to claim 1, the outer end of the cross-sectional enlargement (2) is formed by a plane (14 a) which is oblique to an axial direction.
 13. A method for producing a reinforcing element for concrete construction in the form of a set bolt which is formed with a rod-shaped section (1) with a cross-sectional enlargement (2) on an end thereof, comprising producing the rod-shaped section (1) with a profiling (4), and attaching the cross-sectional enlargement (2) on the end by engaging an outer profile (4) of the rod-shaped section (1) in a form-locking manner with an inside profile (5) of the cross-sectional enlargement.
 14. The method according to claim 13, wherein the cross-sectional enlargement (2) is applied by spraying or injection moulding.
 15. The method according to claim 13, wherein the cross-sectional enlargement (2) is firmly connected with the rod-shaped section (1).
 16. The method of claim 14, wherein a tubular extension (2 a) is simultaneously applied by spraying or injection moulding.
 17. The reinforcing element according to claim 5, wherein the tubular extension (2 a) has an axial length which corresponds to at least four times the diameter of the bore (3).
 18. The reinforcing element according to claim 4, wherein the tubular extension (2 a) passes into the cross-sectional enlargement (2) at an angle of less than 60°. 